Research Article New Insights into Benzene Hydrocarbon

Research ArticleNew Insights into Benzene HydrocarbonDecomposition from Fuel Exhaust Using Self-SupportRay Polarization Plasma with Nano-TiO2

Tao Zhu1 Wenjuan Zhao1 Wenjing Zhang2 Ni Xia1 and Xiaoyang Li1

1School of Chemical amp Environmental Engineering China University of Mining amp Technology-Beijing Ding 11Xueyuan Road Haidian District Beijing 100083 China2Chinese Academy for Environmental Planning No 8 Dayangfang Road Chaoyang District Beijing 100012 China

Correspondence should be addressed to Tao Zhu bambooztcumtbeducn

Received 17 June 2015 Revised 11 August 2015 Accepted 3 September 2015

Academic Editor Hao Tang

Copyright copy 2015 Tao Zhu et alThis is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A new insight into self-support ray polarization (SSRP) of nonthermal plasma for benzene hydrocarbon decomposition in fuelexhaust was put forward A wire-tube dielectric barrier discharge (DBD) AC plasma reactor was used at atmospheric pressure androom temperatureThe catalyst wasmade of nano-TiO

2and ceramic raschig rings Nano-TiO

2was prepared as an active component

by ourselves in the laboratory Ceramic raschig rings were selected for catalyst support materialsThen the catalyst was packed intononthermal plasma (NTP) reactor Six aspects benzene initial concentration gas flux electric field strength removal efficiencyozone output andCO

2selectivity on benzene removal efficiency were investigatedThe results showed SSRP can effectively enhance

benzene removal efficiency The removal efficiency of benzene was up to 99 at electric field strength of 12 kVcm At the sametime SSRP decreases ozone yield and shows a better selectivity of CO

2than the single technology of nonthermal plasmaThe final

products were mostly CO CO2 and H

2O Our research will lay the foundation for SSRP industrial application in the future

1 Introduction

Since 1997 after the use of unleaded gasoline gasoline com-position and chemical composition of automobile emissionsin Beijing have changed Now automobile exhaust pollutantsmainly consist of themixtures of fuel evaporation and incom-plete combustion products Lu et al [1] established the sourcecomponent spectrum of automobile exhaust and the spec-trum of gasoline vapor and liquid gasoline volatile organiccompounds (VOCs) including gasoline diesel and liquefiedpetroleum gas (LPG) as the fuel by sampling on site andthe data normalization processing method It was found thatbenzene toluene xylene 124-trimethyl benzene and otheraromatic compounds have higher proportion in gasoline anddiesel exhaust Some researchers have found that somemem-branes like CNTmembranes could be used to filtrate benzenehydrocarbon [2] Aromatic volatile organic compounds dueto their toxicity and harm on the atmospheric environment

attract widespread concern of scholars at home and abroad[3ndash6]

In recent years nanometer photocatalysis processes forVOCs decomposition have received considerable attentionbecause of low energy consumption high efficiency andno secondary pollution Photochemical reactor is the coreequipment of photocatalysis process and solid phase photo-catalytic oxidation reactor and fixed bed reactor are mainlyused at present However these reactors cannot deal well withVOCs from automobile emission so far Therefore how toimprove ideal photocatalysis reactor has become the key forVOCs decomposition

The author uses self-support ray polarization (SSRP) ofnonthermal plasma (NTP) for benzene hydrocarbon removalin fuel exhaust A wire-tube dielectric barrier discharge(DBD) AC plasma reactor was used at atmospheric pressureand room temperature The catalyst was made of nano-TiO

2

and ceramic raschig rings Nano-TiO2was prepared as an

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 527194 8 pageshttpdxdoiorg1011552015527194

2 Journal of Nanomaterials

Plate film

Dry and heat treatment

Control temperature

PullDeposit

Dropping

Well-proportioned and transparent colloid Steady Sol

13 share of solvent + water + HNO3 23 share of solvent + [Ti(OBu)4] + AcAc

Nano-TiO2 film

Figure 1 Flow chart on preparing nano-TiO2thin film by Sol-Gel method

active component by us in the laboratory Ceramic raschigrings were selected for catalyst support materials Then thecatalyst was packed into nonthermal plasma (NTP) reactor[7]

When imposing external voltage on plasma reactorrsquosdischarge electrode a mess of micro discharges will begenerated along with gas discharge These micro dischargescome with a certain amount of ultraviolet Once the pho-tocatalyst was packed into NTP reactor these ultravioletlights would activate the photocatalysts with gas dischargehappening to treat gaseous VOCs Ceramic raschig rings asthemain carrier of nano-TiO

2photocatalyst lead to chemical

reactions in the photocatalyst surface SSRP generated withplasma happens to promote the photocatalytic reactionPlasma and photocatalyst work together to improve theremoval efficiency of the gaseous pollutants So SSRP has abetter degradation effect than general fixed bed reactor

2 Materials and Methods

21 Materials Preparation Nano-TiO2films were prepared

by the Sol-Gel method in the experiment [8] Flow chart onpreparing nano-TiO

2thin film by Sol-Gel method is given in

Figure 1Precursor solution is as follows 1mol tetrabutyl titanate

(precursor substance) + 12mol ethanol (solvent) + 12molacetylacetone (chelating reagent)

Droplet solution is as follows 6mol ethanol (solvent) +1mol HNO

3(catalyzer) + 25mol distilled water

Droplet solution was dropped slowly into the originalsolution at 35∘C and the whole solution was mixed welltogether The steady Sol would be obtained and then the Solshould be deposited at least 24 hours The packed materials(id 5mm thickness 3mm length 10mm raschig ceramicring) must be washed by microwave cleaning apparatusbefore they were immersed into the Sol Later the packedmaterials were pulled out from the Sol at the speed of15mms to get the nanometer TiO

2filmThe packed materi-

als with nanometer film would be dried at 80∘C for one hourbefore they were put into a muffle furnace to calcine at 450sim600∘C for two hours At last the film gradually refrigeratedto ambient temperature [9]

In this experiment we platted nano-TiO2thin film on the

surface of ceramic raschig rings 3 times and the weight ofnano-TiO

2thin film was 0003 gcm2 Ceramic raschig ring

was selected with length of 1 cm and wall thickness of 1mm

and inner diameter of 5mm as catalyst carrier The structureof ceramic raschig ring is tested by X-Ray Diffraction (XRD)and can be seen in Table 1

22 NTP System The NTP system consisted of a tube-wire packed-bed reactor system an AC power supply acontinuous flow gas supplying system and an electric andgaseous analytical system The schematic diagram of NTPsystem is shown in Figure 2 Dry air (78 N

2 21 O

2)

was used as a balance gas for benzene decomposition Airsupplied from an air compressor was divided into two airflows with each flow rate controlled by a mass flow controller(MFC) One dry air flowwas introduced into a bottle of liquidbenzene to produce saturated benzene The vapor was thenmixed with the other dry air flow in a blender so that benzenewaste gas was diluted to a desired concentration The voltageand current waves were measured by oscilloscope (Tektronix2014) The voltage applied to the reactor was sampled by a12500 1 voltage divider Also the current was determinedfrom the voltage drop across a shunt resistor (R3 = 10 kΩ)connected in series with the grounded electrode In order toobtain the total charge and discharge power simultaneously acapacitor (119862

119898= 2120583F) was placed instead of the shunt resistor

The electrical power provided to the discharge was measuredusing the Q-V Lissajous diagram The power source used inthe experiment is high voltage alternate current power supplywhose frequency is 50Hz ranging from 0 to 30 kV

The NTP packed-bed reactor was shown in Figure 3 Thecoaxial cylindrical NTP reactor was made of an organic-glasstube with an inner diameter of 50mm and wall thicknessof 5mm wrapped by a copper mesh of 50 cm in length asa ground electrode A tungsten wire (15mm in diameters)placed on the axis of NTP reactor served as the innerdischarge electrode The relative humidity of 25 in NTPreactor was controlled by a thermohygrometer

23 Detect Methods Adapt the production to benzenegas concentration detected by Gas Chromatography-MassSpectrometer (produced by American Thermos FinneganTRACE-MS) matching hydrogen flame ion detector (FID)minimum detection quantity can reach 10ndash15 g Chromato-graphic column is 30m long with inner diameter 032mmandDB-1 nonpolar capillary column Choose iodine quantitymethod to determine ozone concentration Use TektronixTDS2014 type oscilloscope to measure discharge parametersin experiment process Use Lissajous method to determine

Journal of Nanomaterials 3

Table 1 Physics characteristics of the packed material raschig ceramic ring

Component Interstitial rate Hygroscopic coefficient Volume density (gsdotcmminus3) Hole rate Quartz Al

2O3

Noncrystal15 35 50 94 59 217 127

(10)

(2) Buffer(3) Benzene liquid bottle

(1) Air compressor

(4) Attemperator(5) Blender(6) NTP reactor

(9) High voltage(10) Oscillograph

(8) Needle valve(7) Mass flow meter

(11) Gas chromatograph

R2

R3

R1

(11)(8)

(8)

(9)

(6)

(7)(7)

(7)

(7)

(3)

(4)

(5)

(2)(1)

Cm

Figure 2 Schematic diagram of NTP system for benzene removal

Gas inExternalelectrode Gas out

Internal electrode

Dielectrictube

Figure 3 NTP reactor Reactor organic-glass tube (id 32mmpacked infilling length of packed materials of 200mm) internalelectrode tungsten filament (id 05mm) external electrode densesteel mesh

discharge power Use the domestic SC-1001 type Gas Chro-matograph to detect CO

2and CO content in final product

matching hydrogen flame ion detector (FID) methanationconverter is connected to the detection top the minimumdetection quantity is 10ndash12 g and linear range is 107 Thesurface characteristic of TiO

2samples was detected by XRD

Evaluation standard of benzene degradation effect isevaluated by the following calculation equations

120578 =

119862

0minus 119862

119862

0

times 100 (1)

119904CO2

=

119862CO2

119899 times (119862

0minus 119862)

times 100 (2)

In (1) 120578 represents removal efficiency of the benzene 119862

0represents benzene gas inlet mass concentration mgm3119862 is the mass concentration of outlet benzene mgm3 In (2)

X-ra

y in

tens

ity

2120579

20 30 40 50 60 70

35083

323880

237206

189119

169773

166539

147903

126451

0102030405060708090100110

Figure 4 XRD of nano-titania

119904CO2

represents the selectivity of CO2after benzene degrada-

tion reaction 119862CO2

represents the quality concentrationafter reaction mgm3 and n represents the carbon atomnumber VOCs molecule contains

3 Results and Discussion

31 Characterization of Nano-TiO2 To carry out XRD phaseanalysis for prepared TiO

2samples XRD spectra are shown

in Figure 4There are two kinds of crystal of rutile and anatasein the phase because of heat treatment temperature of 600∘Cfor TiO

2photocatalyst preparationThemass ratio of anatase

crystal and rutile crystal is 17 3 and anatase crystal is themain component of TiO

2catalysts [10] At the same time


Figure 5 SEMmicrograph of TiO2

XRD detected results show that the average particle size ofanatase crystals of TiO

2is 287 nm and the average particle

size of rutile crystal of TiO2is 351 nm

The nanometer TiO2thin film was inspected and ana-

lyzed by Scan Electric Mirror (SEM made in Japan S-2700) The results of SEM micrograph showed that averageparticulate diameters of TiO

2were less than 100 nm SEM

micrograph of the samples is referred to in Figure 5

32 Effect of Self-Support Photocatalytic on Removal Efficiencyof Benzene Figure 7 shows the relationship between electricfield strength and removal efficiency with or without cata-lysts Benzene removal efficiency is increased to over 80and removal efficiency increases 10 with catalyst comparedto that without catalyst in the conditions of benzene concen-tration (C

0) of 600mgm3 and electric field strength (E) of

9 kVcm Benzene is triggered not only to form C6H5

∙ but toform short carbon chain radicals and molecular fragmentsMedium stops free radicals such as ∙OH ∙O from oxidizingC6H5

∙ molecular fragment short carbon chain and COSome of the free radicals generated from reactants in thestrong electric field happen to be composited again after thereaction zone so that oxidation of benzene is incomplete Ifcatalyst was added in the reaction zone these free radicals aswell as oxygen free radical are absorbed on the surface of thecatalyst before compositing inactivation Oxidation reactionoccurs further and the removal efficiency is higher withcatalyst than the single DBD At lower electric field strengthcorona discharge isweakwithin reactor and corona dischargedistrict concentrates only near corona feeder At this timeultraviolet rays discharged are weaker and the functionof TiO

2photocatalyst is weaker The active free radicals

produced by discharging are limited to the surroundingsof corona district and cannot react collaboratively with thecatalyst of packing surface beyond the corona district Sobenzene removal efficiency is approximate with or withoutcatalyst When electric field strength is gradually enhancedand corona district expands ultraviolet rays discharged areenhanced and catalytic activity gradually increases It isobvious that benzene removal efficiency increases When theelectric field strength rises up to a certain degree catalyst isfully activated and removal efficiency of benzene tends to bestable

(a)

(c)(b)

(d)

101

110

111

200 21

1

(a) 450(b) 600

(c) 700(d) 800

2120579 (∘)

20 30 40 50 60

Figure 6 The result of TiO2thin film by heat treatment

33 Effect of Self-Support Photocatalytic on Ozone Genera-tion Figure 8 shows ozone concentration (119862O

3

) graduallyincreased with the gas flux (VGas) increasing O2 concentra-tion increases in the air with gas flux increasing Under highvoltage energetic electrons are throughout the reactor spaceand they bombard O

2molecule to react as follows

O2+ e 997888rarr ∙O +Ominus (3)

O +O2+M 997888rarr O

3+M (4)

Thus the ozone concentration is in the upward trendIt can be also seen fromFigure 6 that ozone concentration

is lower with catalyst than that without catalysts whenbenzene gas flux entering the reactor is kept the same Itindicates that TiO

2photocatalyst has an inhibitory effect on

ozone formation During the removal of benzene electron-hole pairs are energetic which are from SSRP on the surfaceof the catalyst High energy electrons generated in the gasesdischarge process are preemptively composited with thephoto-induced hole to reduce the amount of high energyelectron which is used to produce ozone in the air So ozoneyield decreases

Figure 9 shows the relationship between benzene initialconcentration (C

0) and ozone concentration (119862O

3

) with orwithout catalyst It can be seen from Figure 8 that ozoneconcentration increases with benzene initial concentration


(a)(b)

5 7 9 11 133

E (kVmiddotcmminus1)

120578(

)

0

20

40

60

80

100

Figure 7 Relationship between electric field strength (E) andremoval efficiency (120578) with or without catalyst (VGas = 100 Lh C

0

= 600mgm3) (a) without catalyst (b) with catalyst

(a)(b)

CO

3(m

gmiddotLminus

1)

50 100 150 200 25000

05

1

15

2

25

3

35

middothminus1)vGas (L

Figure 8 Relationship between gas flux (VGas) and ozone concentra-tion (119862O3 )with or without catalyst (C0 = 600mgm3 E = 12 kVcm)(a) without catalyst (b) with catalyst

decreasing When C0rises C

6H6molecules cost part of the

free electrons and free radicals to affect ozone generationWe found that C

6H6still exists in emission gas in the case

of high O3concentrations through Gas Chromatography-

Mass Spectrometry (GC-MS) It indicates that O3does not

react with C6H6directly That means ozone decomposes into

radical fragments firstly rather than reacting directly withbenzene and free radicals such as ∙OH ∙O play a major roleas oxidantsThis conclusion is supported previously byAssadiet al [11]

34 Effect of Self-Support Photocatalytic on CO2 and COConcentration and CO2 Selectivity Figure 10 shows

the relationship between electric field strength (E) andCO2and CO concentration (119862CO

2

119862CO) with or withoutcatalyst 119862CO

2

and 119862CO increase with the electric fieldstrength increasing When the electric field strength is12 kVcm 119862CO

2

is 35 times higher than 119862CO As thefield strength increases energetic electron O

3 and other

oxidizing radicals increase in the NTP process At the sametime there are a large amount of electron-hole pairs and∙OH ∙O radicals in SSRP process They work together withbenzene molecules to decompose to CO

2and CO It was

found that when the electric field intensity is higher than12 kVcm except of CO CO

2 and H

2O no other products

were found in the emission exhaust through GC-MSFigure 11 shows the relationship between electric field

strength (E) and CO2selectivity (119904CO

2

) with or withoutphotocatalyst 119904CO

2

increases with the electric field strengthincreasing When the electric field strength is 11 kVcm 119904CO

2

is 15 higher with catalyst than that without catalyst ItmeansSSRP is favorable to improving 119904CO

2

SSRP not only improvesthe reaction selectivity of benzene molecules in the plasmaregion and on the surface of the catalyst but also makesbyproducts generated in NTP process oxidize into CO CO

2

in NTP region and on the surface of catalyst finally

4 Reaction Mechanism

Ultraviolet rays coming from plasmarsquos self-support raypolarization provide a good power source for nanometerphotocatalytic materials When the UV radiates nano-TiO

2

photocatalyst the catalystrsquos surface will produce electron andhole which react with O

2or H2O adsorbed on the surface

generating OH free radical as a result and react with VOCS[12] Plasma self-support ray polarization reactor adheres tothe following 3 procedures in treatment of VOCS

(1) Energetic electron bombards VOCS to inspire ionizeand dissociate chemical bond breaking thus playingthe role of damaging VOCS

(2) There exist large amounts of free radicals and ozonein the plasma which oxidize VOCS to generate CO

2

H2O and CO

(3) When the UV radiates nano-TiO2photocatalyst the

catalystrsquos surfacewill produce electron and holewhichreact with O


generating ∙OH free radical as a result and degradedVOCS Chemical reactions are as follows [13]

The wavelength threshold of the light absorbed is3875 nm corresponding to TiO

2band gap of 32 eV When

irradiated by the light whose wavelength is less than or equalto 3875 nm electron is fired on the valence band to cross thegap band and enter the conduction band [14] At the sametime the corresponding hole on the valence band produces[15]

TiO2+ plasma 997888rarr h+ + eminus (5)

Electron-hole pairs have limited life and they will sooncompound the following reaction

h+ + eminus 997888rarr heat (6)


0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(a) Without catalyst

0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(b) With catalyst

Figure 9 Relationship between benzene initial concentration (C0) and ozone concentration (119862O3 ) with or without catalyst (E = 12 kVcm)

(a) (b)(c) (d)

6 7 8 9 10 11 12 135


CCO

2an

dC

CO(m

gmiddotm

3)

0

200

400

600

800

1000

1200

1400

1600

Figure 10 Relationship between electric field strength (E) and CO2

and CO concentration with or without catalyst (C0= 600mgm3

E = 12 kVcm and VGas = 100 Lh) (a) CO2 concentration withoutcatalyst (b) CO

2concentration with catalyst (c) CO concentration

without catalyst and (d) CO concentration with catalyst

Photo-induced hole can be captured by the water orhydroxyl absorbed on the surface of catalyst and then pro-duce ∙OH free radicals

h+ +H2O 997888rarr ∙OH +H+ (7)

h+ +OHminus 997888rarr ∙OH (8)

Without photocatalystWith photocatalyst

7 9 11 135


0

20

40

60

80

100

s CO

2(

)


selectivity (119904CO2 ) with or without photocatalyst (C0= 600mgm3 E

= 12 kVcm and VGas = 100 Lh)

Photo-induced electron is mainly captured by oxygenadsorbed on the surface of catalyst

O2ads 997888rarr 2Oads (9)

O2ads + e

minus997888rarr O

2adsminus (10)

Oads + eminus997888rarr Oads

minus (11)


Part of photo-induced hole can be captured by oxygenadsorbed on the surface of catalyst at the same time

Oadsminus+ h+ 997888rarr Oads (12)

eminus +H2O2997888rarr 2OH∙ (13)

O2

minus+H+ 997888rarr HO

2

∙ (14)

OH∙ HO2

∙ h+ plasma and so forth as the strongestoxidizing oxidants join some other free radicals to affectVOCs

OH∙HO2

∙ h+ plasma etc +VOCs 997888rarr sdot sdot sdot

997888rarr CO2+H2O

(15)

5 Conclusions

The authors use SSRP of NTP for benzene hydrocarbonremoval in fuel exhaust A wire-tube dielectric barrier dis-charge (DBD) AC plasma reactor was used at atmosphericpressure and room temperature The catalyst was made ofnano-TiO


2was pre-

pared as an active component by ourselves in the laboratoryCeramic raschig rings were selected for catalyst supportmaterials Based on a series of experiments we draw thefollowing conclusions

(1) SSRP increases with external electric field strengthincreasing When electric field strength is 12 kVcmbenzene removal efficiency is up to 99

(2) Ozone is a typical byproduct in the NTP processSSRP shows inhibitory effects on the generation ofozone

(3) 119862CO2

119862CO and 119904CO2

increase with the electric fieldstrength increasing in the products SSRP shows agood characteristic to improve 119904CO

2

and to promotebenzene removal efficiency

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Authorsrsquo Contribution

T Zhu and W J Zhang contributed to this work as cor-responding authors and they conceived and designed theexperiments W J Zhao X Ni and X Y Li performed theexperiments T Zhu and W J Zhao analyzed the data W JZhang contributed reagentsmaterialsanalysis tools and WJ Zhao wrote the paper

Acknowledgments

This work was supported by Special Research Funds forEnvironmental Protection Public Welfare (no 201409004)the National Natural Science Foundation of China (no

51108453) Program for New Century Excellent Talents inUniversity (no NCET120967) Beijing Outstanding TalentTraining Project (no 2012ZG81) and the FundamentalResearch Funds for the Central Universities (no 2009QH03)Thanks are due toDr Annie Zeng inWest VirginiaUniversityfor providing language help and for proofreading the paper

References

[1] S H Lu Y H Bai and G S Zhang ldquoStudy on characteristics ofVOCs source profiles of vehicle exhaust and gasoline emissionrdquoActa Scientiarum Naturalism Universities Pekinensis vol 39 pp507ndash511 2003

[2] A Saha C M Jiang and A A Martı ldquoCarbon nanotubenetworks on different platformsrdquo Carbon vol 79 no 1 pp 1ndash18 2014

[3] A M Vandenbroucke M Mora C Jimenez-Sanchidrian etal ldquoTCE abatement with a plasma-catalytic combined systemusingMnO

2as catalystrdquoAppliedCatalysis B Environmental vol

156-157 pp 94ndash100 2014[4] T Zhu R Chen N Xia et al ldquoVolatile organic compounds

emission control in industrial pollution source using plasmatechnology coupledwith F-TiO

2120574-Al2O3rdquoEnvironmental Tech-

nology vol 36 pp 1405ndash1413 2015[5] F Rahmani M Haghighi and P Estifaee ldquoSynthesis and char-

acterization of PtAl2O3-CeO

2nanocatalyst used for toluene

abatement from waste gas streams at low temperature con-ventional vs plasma-ultrasound hybrid synthesis methodsrdquoMicroporous and Mesoporous Materials vol 185 pp 213ndash2232014

[6] T Zhu J Li W Liang and Y Jin ldquoSynergistic effect ofcatalyst for oxidation removal of toluenerdquo Journal of HazardousMaterials vol 165 no 1ndash3 pp 1258ndash1260 2009

[7] T Zhu D Y Xu X W He et al ldquoDecomposition of benzene indry air by super-imposed barrier discharge nonthermal plasma-photocatalytic systemrdquoFresenius Environmental Bulletin vol 19no 7 pp 1275ndash1282 2010

[8] H B Zhang K Li T H Sun J Jia Z Lou and L FengldquoRemoval of styrene using dielectric barrier discharge plasmascombined with sol-gel prepared TiO

2coated 120574-Al

2O3rdquo Chemi-

cal Engineering Journal vol 241 pp 92ndash102 2014[9] T Zhu L Lu Y Dai et al ldquoPreparation for nano-titania

catalyst and its application for benzene decompositionrdquo NatureEnvironment and Pollution Technology vol 12 no 4 pp 675ndash678 2013

[10] K Zhang X F Du M B Katz et al ldquoCreating high qualityCaTiO

2-B (CaTi

5O11) andTiO

2-B epitaxial thin films by pulsed

laser depositionrdquo Chemical Communications vol 51 no 41 pp8584ndash8587 2015

[11] A A Assadi J Palau A Bouzaza J Penya-Roja V Martinez-Soriac and D Wolbert ldquoAbatement of 3-methylbutanal andtrimethylamine with combined plasma and photocatalysis ina continuous planar reactorrdquo Journal of Photochemistry andPhotobiology A Chemistry vol 282 pp 1ndash8 2014

[12] J Palau A A Assadi J M Penya-Roja A Bouzaza DWolbertand V Martınez-Soria ldquoIsovaleraldehyde degradation usingUVphotocatalytic and dielectric barrier discharge reactors andtheir combinationsrdquo Journal of Photochemistry and Photobiol-ogy A Chemistry vol 299 pp 110ndash117 2015


[13] D Lopatik D Marinov O Guaitella A Rousseau and JRopcke ldquoOn the reactivity of plasma-treated photo-catalyticTiO2surfaces for oxidation of C

2H2and COrdquo Journal of Physics

D Applied Physics vol 46 no 25 pp 203ndash208 2013[14] B Dou F Bin C Wang Q Jia and J Li ldquoDischarge charac-

teristics and abatement of volatile organic compounds usingplasma reactor packed with ceramic Raschig ringsrdquo Journal ofElectrostatics vol 71 no 5 pp 939ndash944 2013

[15] A A Assadi A Bouzaza C Vallet and D Wolbert ldquoUseof DBD plasma photocatalysis and combined DBD plasmaphotocatalysis in a continuous annular reactor for isovaleralde-hyde eliminationmdashsynergetic effect and byproducts identifica-tionrdquo Chemical Engineering Journal vol 254 pp 124ndash132 2014

Submit your manuscripts athttpwwwhindawicom

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NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


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CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


Plate film

Dry and heat treatment

Control temperature

PullDeposit

Dropping

Well-proportioned and transparent colloid Steady Sol

13 share of solvent + water + HNO3 23 share of solvent + [Ti(OBu)4] + AcAc

Nano-TiO2 film

Figure 1 Flow chart on preparing nano-TiO2thin film by Sol-Gel method

active component by us in the laboratory Ceramic raschigrings were selected for catalyst support materials Then thecatalyst was packed into nonthermal plasma (NTP) reactor[7]

When imposing external voltage on plasma reactorrsquosdischarge electrode a mess of micro discharges will begenerated along with gas discharge These micro dischargescome with a certain amount of ultraviolet Once the pho-tocatalyst was packed into NTP reactor these ultravioletlights would activate the photocatalysts with gas dischargehappening to treat gaseous VOCs Ceramic raschig rings asthemain carrier of nano-TiO

2photocatalyst lead to chemical

reactions in the photocatalyst surface SSRP generated withplasma happens to promote the photocatalytic reactionPlasma and photocatalyst work together to improve theremoval efficiency of the gaseous pollutants So SSRP has abetter degradation effect than general fixed bed reactor

2 Materials and Methods

21 Materials Preparation Nano-TiO2films were prepared

by the Sol-Gel method in the experiment [8] Flow chart onpreparing nano-TiO

2thin film by Sol-Gel method is given in

Figure 1Precursor solution is as follows 1mol tetrabutyl titanate

(precursor substance) + 12mol ethanol (solvent) + 12molacetylacetone (chelating reagent)

Droplet solution is as follows 6mol ethanol (solvent) +1mol HNO

3(catalyzer) + 25mol distilled water

Droplet solution was dropped slowly into the originalsolution at 35∘C and the whole solution was mixed welltogether The steady Sol would be obtained and then the Solshould be deposited at least 24 hours The packed materials(id 5mm thickness 3mm length 10mm raschig ceramicring) must be washed by microwave cleaning apparatusbefore they were immersed into the Sol Later the packedmaterials were pulled out from the Sol at the speed of15mms to get the nanometer TiO

2filmThe packed materi-

als with nanometer film would be dried at 80∘C for one hourbefore they were put into a muffle furnace to calcine at 450sim600∘C for two hours At last the film gradually refrigeratedto ambient temperature [9]

In this experiment we platted nano-TiO2thin film on the

surface of ceramic raschig rings 3 times and the weight ofnano-TiO

2thin film was 0003 gcm2 Ceramic raschig ring

was selected with length of 1 cm and wall thickness of 1mm

and inner diameter of 5mm as catalyst carrier The structureof ceramic raschig ring is tested by X-Ray Diffraction (XRD)and can be seen in Table 1

22 NTP System The NTP system consisted of a tube-wire packed-bed reactor system an AC power supply acontinuous flow gas supplying system and an electric andgaseous analytical system The schematic diagram of NTPsystem is shown in Figure 2 Dry air (78 N

2 21 O

2)

was used as a balance gas for benzene decomposition Airsupplied from an air compressor was divided into two airflows with each flow rate controlled by a mass flow controller(MFC) One dry air flowwas introduced into a bottle of liquidbenzene to produce saturated benzene The vapor was thenmixed with the other dry air flow in a blender so that benzenewaste gas was diluted to a desired concentration The voltageand current waves were measured by oscilloscope (Tektronix2014) The voltage applied to the reactor was sampled by a12500 1 voltage divider Also the current was determinedfrom the voltage drop across a shunt resistor (R3 = 10 kΩ)connected in series with the grounded electrode In order toobtain the total charge and discharge power simultaneously acapacitor (119862

119898= 2120583F) was placed instead of the shunt resistor

The electrical power provided to the discharge was measuredusing the Q-V Lissajous diagram The power source used inthe experiment is high voltage alternate current power supplywhose frequency is 50Hz ranging from 0 to 30 kV

The NTP packed-bed reactor was shown in Figure 3 Thecoaxial cylindrical NTP reactor was made of an organic-glasstube with an inner diameter of 50mm and wall thicknessof 5mm wrapped by a copper mesh of 50 cm in length asa ground electrode A tungsten wire (15mm in diameters)placed on the axis of NTP reactor served as the innerdischarge electrode The relative humidity of 25 in NTPreactor was controlled by a thermohygrometer

23 Detect Methods Adapt the production to benzenegas concentration detected by Gas Chromatography-MassSpectrometer (produced by American Thermos FinneganTRACE-MS) matching hydrogen flame ion detector (FID)minimum detection quantity can reach 10ndash15 g Chromato-graphic column is 30m long with inner diameter 032mmandDB-1 nonpolar capillary column Choose iodine quantitymethod to determine ozone concentration Use TektronixTDS2014 type oscilloscope to measure discharge parametersin experiment process Use Lissajous method to determine




2O3

Noncrystal15 35 50 94 59 217 127

(10)


(1) Air compressor





R2

R3

R1

(11)(8)

(8)

(9)

(6)

(7)(7)

(7)

(7)

(3)

(4)

(5)

(2)(1)

Cm



Internal electrode

Dielectrictube







120578 =

119862

0minus 119862

119862

0

times 100 (1)

119904CO2

=

119862CO2

119899 times (119862

0minus 119862)

times 100 (2)



X-ra

y in

tens

ity

2120579

20 30 40 50 60 70

35083

323880

237206

189119

169773

166539

147903

126451

0102030405060708090100110


119904CO2



























(a)

(c)(b)

(d)

101

110

111

200 21

1

(a) 450(b) 600

(c) 700(d) 800

2120579 (∘)

20 30 40 50 60



3





3+M (4)







3



(a)(b)

5 7 9 11 133


120578(

)

0

20

40

60

80

100


0


(a)(b)

CO

3(m

gmiddotLminus

1)

50 100 150 200 25000

05

1

15

2

25

3

35













2


2


2


3 and other


2and CO It was


2 and H




2


2


2


2


2




2






2

H2O and CO












0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)


0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(b) With catalyst


(a) (b)(c) (d)

6 7 8 9 10 11 12 135


CCO

2an

dC

CO(m

gmiddotm

3)

0

200

400

600

800

1000

1200

1400

1600







h+ +H2O 997888rarr ∙OH +H+ (7)



7 9 11 135


0

20

40

60

80

100

s CO

2(

)






O2ads + e

minus997888rarr O

2adsminus (10)


minus (11)





O2


2

∙ (14)

OH∙ HO2


OH∙HO2


997888rarr CO2+H2O

(15)

5 Conclusions



2was pre-




(3) 119862CO2

119862CO and 119904CO2


2






Acknowledgments



References















2coated 120574-Al

2O3rdquo Chemi-




2-B (CaTi

5O11) andTiO


















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






2O3

Noncrystal15 35 50 94 59 217 127

(10)


(1) Air compressor





R2

R3

R1

(11)(8)

(8)

(9)

(6)

(7)(7)

(7)

(7)

(3)

(4)

(5)

(2)(1)

Cm



Internal electrode

Dielectrictube







120578 =

119862

0minus 119862

119862

0

times 100 (1)

119904CO2

=

119862CO2

119899 times (119862

0minus 119862)

times 100 (2)



X-ra

y in

tens

ity

2120579

20 30 40 50 60 70

35083

323880

237206

189119

169773

166539

147903

126451

0102030405060708090100110


119904CO2



























(a)

(c)(b)

(d)

101

110

111

200 21

1

(a) 450(b) 600

(c) 700(d) 800

2120579 (∘)

20 30 40 50 60



3





3+M (4)







3



(a)(b)

5 7 9 11 133


120578(

)

0

20

40

60

80

100


0


(a)(b)

CO

3(m

gmiddotLminus

1)

50 100 150 200 25000

05

1

15

2

25

3

35













2


2


2


3 and other


2and CO It was


2 and H




2


2


2


2


2




2






2

H2O and CO












0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)


0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(b) With catalyst


(a) (b)(c) (d)

6 7 8 9 10 11 12 135


CCO

2an

dC

CO(m

gmiddotm

3)

0

200

400

600

800

1000

1200

1400

1600







h+ +H2O 997888rarr ∙OH +H+ (7)



7 9 11 135


0

20

40

60

80

100

s CO

2(

)






O2ads + e

minus997888rarr O

2adsminus (10)


minus (11)





O2


2

∙ (14)

OH∙ HO2


OH∙HO2


997888rarr CO2+H2O

(15)

5 Conclusions



2was pre-




(3) 119862CO2

119862CO and 119904CO2


2






Acknowledgments



References















2coated 120574-Al

2O3rdquo Chemi-




2-B (CaTi

5O11) andTiO


















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



















(a)

(c)(b)

(d)

101

110

111

200 21

1

(a) 450(b) 600

(c) 700(d) 800

2120579 (∘)

20 30 40 50 60



3





3+M (4)







3



(a)(b)

5 7 9 11 133


120578(

)

0

20

40

60

80

100


0


(a)(b)

CO

3(m

gmiddotLminus

1)

50 100 150 200 25000

05

1

15

2

25

3

35













2


2


2


3 and other


2and CO It was


2 and H




2


2


2


2


2




2






2

H2O and CO












0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)


0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(b) With catalyst


(a) (b)(c) (d)

6 7 8 9 10 11 12 135


CCO

2an

dC

CO(m

gmiddotm

3)

0

200

400

600

800

1000

1200

1400

1600







h+ +H2O 997888rarr ∙OH +H+ (7)



7 9 11 135


0

20

40

60

80

100

s CO

2(

)






O2ads + e

minus997888rarr O

2adsminus (10)


minus (11)





O2


2

∙ (14)

OH∙ HO2


OH∙HO2


997888rarr CO2+H2O

(15)

5 Conclusions



2was pre-




(3) 119862CO2

119862CO and 119904CO2


2






Acknowledgments



References















2coated 120574-Al

2O3rdquo Chemi-




2-B (CaTi

5O11) andTiO


















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a)(b)

5 7 9 11 133


120578(

)

0

20

40

60

80

100


0


(a)(b)

CO

3(m

gmiddotLminus

1)

50 100 150 200 25000

05

1

15

2

25

3

35













2


2


2


3 and other


2and CO It was


2 and H




2


2


2


2


2




2






2

H2O and CO












0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)


0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(b) With catalyst


(a) (b)(c) (d)

6 7 8 9 10 11 12 135


CCO

2an

dC

CO(m

gmiddotm

3)

0

200

400

600

800

1000

1200

1400

1600







h+ +H2O 997888rarr ∙OH +H+ (7)



7 9 11 135


0

20

40

60

80

100

s CO

2(

)






O2ads + e

minus997888rarr O

2adsminus (10)


minus (11)





O2


2

∙ (14)

OH∙ HO2


OH∙HO2


997888rarr CO2+H2O

(15)

5 Conclusions



2was pre-




(3) 119862CO2

119862CO and 119904CO2


2






Acknowledgments



References















2coated 120574-Al

2O3rdquo Chemi-




2-B (CaTi

5O11) andTiO


















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)


0mgmiddotmminus3

600mgmiddotmminus3

1500mgmiddotmminus3

0

05

1

15

2

25

3

35

50 100 150 200 2500


CO

3(m

gmiddotLminus

1)

(b) With catalyst


(a) (b)(c) (d)

6 7 8 9 10 11 12 135


CCO

2an

dC

CO(m

gmiddotm

3)

0

200

400

600

800

1000

1200

1400

1600







h+ +H2O 997888rarr ∙OH +H+ (7)



7 9 11 135


0

20

40

60

80

100

s CO

2(

)






O2ads + e

minus997888rarr O

2adsminus (10)


minus (11)





O2


2

∙ (14)

OH∙ HO2


OH∙HO2


997888rarr CO2+H2O

(15)

5 Conclusions



2was pre-




(3) 119862CO2

119862CO and 119904CO2


2






Acknowledgments



References















2coated 120574-Al

2O3rdquo Chemi-




2-B (CaTi

5O11) andTiO


















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







O2


2

∙ (14)

OH∙ HO2


OH∙HO2


997888rarr CO2+H2O

(15)

5 Conclusions



2was pre-




(3) 119862CO2

119862CO and 119904CO2


2






Acknowledgments



References















2coated 120574-Al

2O3rdquo Chemi-




2-B (CaTi

5O11) andTiO


















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article New Insights into Benzene Hydrocarbon